Question:
In the first proof reading of a book containing 300 pages the following distribution of misprints was obtained:
Find the average number of misprints per page
Solution:
Let the assume mean be $A=2$.
We know that mean, $\bar{X}=A+\frac{1}{N} \sum_{i=1}^{n} f_{i} d_{i}$
Now, we have $N=\sum f_{i}=300, \sum f_{i} d_{i}=-381$ and $A=2$.
Putting the values in above formula, we have
$\bar{X}=A+\frac{1}{N} \sum_{i=1}^{n} f_{i} d_{i}$
$=2+\frac{1}{300} \times(-381)$
$=2-\frac{381}{300}$
$=2-1.27$
$=0.73$
Hence, the mean number of students absent per day is 0.73.
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